Co-translational membrane association of the <i>Escherichia coli</i> SRP receptor

Bercovich-Kinori, Adi; Bibi, Eitan

doi:10.1242/jcs.166116

Cited by 12 publications

(6 citation statements)

References 45 publications

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“…The posttranslational role of SRP during the insertion of small membrane proteins could also include a posttargeting function. Such a role of SRP has been proposed based on in vivo experiments [82][83][84][85]. In this model, mRNAs coding for membrane proteins would be targeted to already membrane-bound ribosomes for translation and SRP would be required for the subsequent insertion [86].…”

Section: Discussionmentioning

confidence: 99%

Posttranslational insertion of small membrane proteins by the bacterial signal recognition particle

et al. 2020

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Small membrane proteins represent a largely unexplored yet abundant class of proteins in pro-and eukaryotes. They essentially consist of a single transmembrane domain and are associated with stress response mechanisms in bacteria. How these proteins are inserted into the bacterial membrane is unknown. Our study revealed that in Escherichia coli, the 27amino-acid-long model protein YohP is recognized by the signal recognition particle (SRP), as indicated by in vivo and in vitro site-directed cross-linking. Cross-links to SRP were also observed for a second small membrane protein, the 33-amino-acid-long YkgR. However, in contrast to the canonical cotranslational recognition by SRP, SRP was found to bind to YohP posttranslationally. In vitro protein transport assays in the presence of a SecY inhibitor and proteoliposome studies demonstrated that SRP and its receptor FtsY are essential for the posttranslational membrane insertion of YohP by either the SecYEG translocon or by the YidC insertase. Furthermore, our data showed that the yohP mRNA localized preferentially and translation-independently to the bacterial membrane in vivo. In summary, our data revealed that YohP engages an unique SRP-dependent posttranslational insertion pathway that is likely preceded by an mRNA targeting step. This further highlights the enormous plasticity of bacterial protein transport machineries.

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Section: Discussionmentioning

confidence: 99%

Posttranslational insertion of small membrane proteins by the bacterial signal recognition particle

et al. 2020

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“…Co-translational targeting of nascent membrane proteins to the endoplasmic reticulum of eukaryotic cells or the plasma membrane of bacteria is elicited via the signal recognition particle (SRP) pathway.S RP rapidly scans translating ribo-somes and targets those synthesizing membrane proteins to the protein-conducting channel (SecYEG in bacteria), located in the membrane,b ya ni nteraction with the SRP receptor,F tsY in bacteria. FtsY must be bound to the membrane to be functional, [1] that is,torecruit SRP and form the transfer complex at the SecYEG translocon. [2] Tw o regions of FtsY,t he N-terminal Ad omain and ar egion at the interface between Aand Ndomain (membrane targeting sequence,M TS) ( Figure 1a), are involved in lipid binding as shown by cross-linking experiments.…”

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confidence: 99%

Electrostatics and Intrinsic Disorder Drive Translocon Binding of the SRP Receptor FtsY

et al. 2016

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Integral membrane proteins in bacteria are co‐translationally targeted to the SecYEG translocon for membrane insertion via the signal recognition particle (SRP) pathway. The SRP receptor FtsY and its N‐terminal A domain, which is lacking in any structural model of FtsY, were studied using NMR and fluorescence spectroscopy. The A domain is mainly disordered and highly flexible; it binds to lipids via its N terminus and the C‐terminal membrane targeting sequence. The central A domain binds to the translocon non‐specifically and maintains disorder. Translocon targeting and binding of the A domain is driven by electrostatic interactions. The intrinsically disordered A domain tethers FtsY to the translocon, and because of its flexibility, allows the FtsY NG domain to scan a large area for binding to the NG domain of ribosome‐bound SRP, thereby promoting the formation of the quaternary transfer complex at the membrane.

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“…Low-intensity bands underneath the major GlpG construct bands were observed by Western blotting and attributed to small populations of truncated GlpG. This is commonly observed within preparations of RNCs by SecM-based stalling, 1 , 57 caused by digestion with remaining proteases during purification. Notably, when the GlpG constructs were released from the ribosome, they became more prone to degradation, suggesting that the constructs are stabilized and/or protected by the ribosome to protease digestion ( Figure 2 b).…”

Section: Resultsmentioning

confidence: 96%

Capturing Membrane Protein Ribosome Nascent Chain Complexes in a Native-like Environment for Co-translational Studies

et al. 2020

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Co-translational folding studies of membrane proteins lag behind cytosolic protein investigations largely due to the technical difficulty in maintaining membrane lipid environments for correct protein folding. Stalled ribosome-bound nascent chain complexes (RNCs) can give snapshots of a nascent protein chain as it emerges from the ribosome during biosynthesis. Here, we demonstrate how SecM-facilitated nascent chain stalling and native nanodisc technologies can be exploited to capture in vivo -generated membrane protein RNCs within their native lipid compositions. We reveal that a polytopic membrane protein can be successfully stalled at various stages during its synthesis and the resulting RNC extracted within either detergent micelles or diisobutylene–maleic acid co-polymer native nanodiscs. Our approaches offer tractable solutions for the structural and biophysical interrogation of nascent membrane proteins of specified lengths, as the elongating nascent chain emerges from the ribosome and inserts into its native lipid milieu.

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Co-translational membrane association of the Escherichia coli SRP receptor

Cited by 12 publications

References 45 publications

Posttranslational insertion of small membrane proteins by the bacterial signal recognition particle

Posttranslational insertion of small membrane proteins by the bacterial signal recognition particle

Electrostatics and Intrinsic Disorder Drive Translocon Binding of the SRP Receptor FtsY

Capturing Membrane Protein Ribosome Nascent Chain Complexes in a Native-like Environment for Co-translational Studies

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